The present invention relates to an aerial photograph image pickup method and an aerial photograph image pickup apparatus by a small Unmanned Aerial Vehicles (UAV).
In the photography from the air above or the surveying from the air above, the information which cannot be acquired by the photography from the ground or the surveying on the ground can be acquired, and the photography is possible in an off-limits area, or the information in an area where the surveying is difficult can be acquired. Further, in recent years, because of the improvement in performance of a small flying object as remote controlled such as a tiny plane or a small-scale helicopter, or the like, the improvement in a remote control technology, and further, the improvement in performance of an image pickup device, the promotion of the miniaturization, and others, the image pickup device can be mounted in a small flying object. By remotely controlling the flying object, the photography from the air above can be performed in an unmanned manner. Furthermore, the flying object can make an autonomous flight in accordance with a preset flight schedule.
In case of performing the photography by a small flying object, although it is desired for a body to be horizontal, the body actually has a light weight, and the body is often swept away by the wind, or the body is often tilted. Therefore, in a fixedly mounted image pickup device, an optical axis is tilted depending on a state of the body, and a tilt direction is not fixed.
In case of preparing an image in a wide range, or in case of preparing a stereo image, two images adjacent to each other are overlapped, a connecting point (a tie point) common to the two images in the overlap portion is extracted, and based on the tie point, the images are combined. However, as described above, when the images taken in a state that an optical axis is tilted or a tilt angle or a tilt direction is not fixed are sequentially combined with each other, a resultant image in the extensive range is distorted or curved, and there is a problem that a correct combined image cannot be obtained.